Intresting!!.. I went back to old boot driver fcp 5.1.4 and old drivers and also could then playback 3 streams of 720P8bit/10bit and record as much as I wanted..
with fcs2 and BM6.2 drivers I get disk speed errors.. trashed prefs.. restarted and it seems ok.. switch rez to say PAL, capture.. switch back.. its back.. Not impressed.
Never thought about being a conflict with the cards! how did you conclude this?
Currently boot off external with 5.1.4 and 6.1 on for stable capture.. then reboot to edit clips. Not ideal!
Easy setup does not setup !.. possibly a fcp bug though.
static clicks.. yes… but thought that may be the fridge :-/